Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Atmospheric Vapor Pressure Deficit Outweighs Soil Moisture Deficit in Controlling Global Ecosystem Water Use Efficiency","authors":"Chao Li,&nbsp;Dahong Zhang,&nbsp;Shiqiang Zhang,&nbsp;Yanan Wen,&nbsp;Wenhui Wang,&nbsp;Youdong Chen,&nbsp;Jian Peng","doi":"10.1029/2024JG008605","DOIUrl":"https://doi.org/10.1029/2024JG008605","url":null,"abstract":"<p>High vapor pressure deficit (VPD) and low soil moisture (SM) lead to soil and atmospheric droughts, which can stress carbon-water coupling in terrestrial ecosystems. However, the strong collinearity between VPD and SM, particularly under certain climatic conditions, makes it challenging to disentangle their independent contributions to carbon and water dynamics in land-atmosphere interactions. This study aimed to clarify the long-term independent response of global vegetation carbon-water coupling, based on ecosystem water-use efficiency (WUE_E) and plant canopy water-use efficiency (WUE_Et), to decoupled VPD and SM from 1982 to 2100. WUE_E is defined as the ratio of ecosystem gross primary productivity to evapotranspiration, while WUE_Et is defined as the ratio of ecosystem gross primary productivity to vegetation transpiration. The results indicate that from 1982 to 2018, both before and after the decoupling of VPD and SM, over 64% of global vegetation zones experienced stronger atmospheric moisture stress from VPD than soil drought stress from SM, consistently impacting WUE_E and WUE_Et. The influence of VPD on WUE_E and WUE_Et gradually declined, while the influence of SM presented a tendency to increase. The small difference in the responses of WUE_E and WUE_Et to VPD and SM is attributed to the strong collinearity between WUE_E and WUE_Et. The effects of VPD and SM on WUE_E and WUE_Et varied across vegetation cover gradients, biomes, and climatic zones. As atmospheric and soil drought intensifies in the coming decades, the effects of VPD on WUE_E and WUE_Et stress are stronger than those of SM across all four socio-economic shared pathway (SSP) scenarios. In the high SSP scenarios (SSP5-8.5 for WUE_E and SSP3-7.0 for WUE_Et), the dominant influence of VPD is expected to expand.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143595245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights Into Nature-Based Climate Solutions: Managing Forests for Climate Resilience and Carbon Stability","authors":"Bailey A. Murphy,&nbsp;Christine R. Rollinson,&nbsp;Michael C. Dietze,&nbsp;Christina L. Staudhammer,&nbsp;Nicolena R. VonHedemann,&nbsp;Courtney A. Schultz,&nbsp;William J. Kleindl,&nbsp;Ankur R. Desai","doi":"10.1029/2024JG008391","DOIUrl":"https://doi.org/10.1029/2024JG008391","url":null,"abstract":"<p>Successful implementation of forest management as a nature-based climate solution is dependent on the durability of management-induced changes in forest carbon storage and sequestration. As forests face unprecedented stability risks in the face of ongoing climate change, much remains unknown regarding how management will impact forest stability, or how interactions with climate might shift the response of forests to management across spatiotemporal scales. Here, we used a process-based model to simulate multidecadal projections of forest dynamics in response to changes in management and climate. Simulations were conducted across gradients in forest type, edaphic factors, and management intensity under two alternate radiative forcing scenarios (RCP4.5 and RCP8.5). This allowed for the quantification of forest stability shifts in response to climate change, and the role of management in modulating that response, where ecosystem stability is characterized as the resilience and temporal stability of net primary production, aboveground biomass, and soil carbon. Our results indicate that forest structure is primarily shaped by management, but the same management strategy often produced divergent structures over time, due to interactions with regional climate change. We found that management can be used to increase stability and minimize the release of stored carbon by reducing mortality, but also highlight the regional dependency of management-induced changes in resilience to climate change.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008391","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143581507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes of Nitrous Oxide Dynamics Induced by Typhoons: A Case in Zhanjiang Bay, China","authors":"Shangjun Cai,&nbsp;Qibin Lao,&nbsp;Xuan Lu,&nbsp;Xin Zhou,&nbsp;Guangzhe Jin,&nbsp;Chunqing Chen,&nbsp;Fajin Chen","doi":"10.1029/2024JG008617","DOIUrl":"https://doi.org/10.1029/2024JG008617","url":null,"abstract":"<p>Under the influence of global climate change, both the frequency and intensity of typhoons are increasing. This study examines the impact of the typhoon on nitrous oxide (N₂O) dynamics in coastal bays, which are the most active areas of N₂O production in the ocean. Employing the ¹⁵N stable isotope labeling technique, coupled with stable isotope mass spectrometry and analysis of key biogeochemical parameters, we conducted a series of five continuous cruises before (one cruise) and after typhoons Chaba (four cruises) in Zhanjiang Bay, a semiclosed coastal bay in the northern South China Sea. Our results showed that the landfall of the typhoon led to a sharp decrease in N₂O concentration in Zhanjiang Bay. However, the typhoon also triggered a substantial production of N₂O in both water column and sedimentary environments, therefore facilitating a rapid recovery of N₂O levels within a short period. In the water column, typhoon-induced enhancement of in situ N₂O production could be attributed to a substantial input of nutrients and terrestrial particles, which creates an anaerobic or hypoxic microenvironment conducive to N₂O production. Concurrently, in the sediment, the deposition of particles derived from typhoon-induced phytoplankton blooms introduces a large amount of fresh particulate organic matter, further promoting N₂O production. Our findings suggest that typhoons are an efficient nitrogen removal process, which has been previously underestimated. By elucidating aspects of the nitrogen cycle in bays during typhoons, this research aids in shaping policies to mitigate greenhouse gas emissions triggered by typhoons.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143571245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic Carbon Remineralization and Calcium Carbonate Production Rates in the Red Sea Computed From Oxygen and Alkalinity Utilizations","authors":"Salma Elageed,&nbsp;Abdirahman M. Omar,&nbsp;Emil Jeansson,&nbsp;Ingunn Skjelvan,&nbsp;Knut Barthel,&nbsp;Truls Johannessen","doi":"10.1029/2024JG008357","DOIUrl":"https://doi.org/10.1029/2024JG008357","url":null,"abstract":"<p>Organic carbon remineralization rate (OCRR) and the calcium carbonate production rate (CCPR) are influential variables on the efficiency of the biological carbon pump (BCP) but are not well understood in Red Sea. We used historical cruise data of carbonate chemistry, oxygen, and transient tracers from five locations along the north–south central axis of the Red Sea to estimate OCRR and CCPR from tracer-based water mean ages (Γ), apparent oxygen utilization (AOU), and alkalinity utilization (AU). This resulted in the first basin-wide and depth-resolving (100–1,000 m) OCRR and CCPR estimates. Spatial distributions for Γ, AOU, and AU were strongly influenced by the large-scale circulation and showed maxima intermediate depths (400–500 m). Conversely, OCRR and CCPR showed no statistically significant latitudinal differences and peaked (6.5 ± 4.3 and 11.9 ± 4.6 mmol C m⁻³ yr⁻¹, respectively) at 100-m depth, which decreased to nearly constant values (3.8 ± 0.7 and 1.4 ± 0.3 mmol C m⁻³ yr⁻¹, respectively) at 300 m and deeper. By depth-integrating CCPR, we estimated annual calcium carbonate production (CCP) of (0.8 ± 0.3) × 10¹² mol, or 0.6% of global ocean production, in the Red Sea, which has only 0.12% of the world ocean area. High correlation between AU and Γ indicated in situ alkalinity removal taking place also in subsurface and deep waters, probably due to chemical precipitation, which has been previously reported for the area. CCP-induced AU affects the carbonate chemistry in the Red Sea water column, and we hypothesize that it also impacts that of the Gulf of Aden through the outflowing Red Sea Outflow Water.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143565083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alternating Drying and Flowing Phases Control Stream Metabolism Through Short- and Long-Term Effects: Insights From a River Network","authors":"Naiara López-Rojo,&nbsp;Romain Sarremejane,&nbsp;Arnaud Foulquier,&nbsp;Gabriel Singer,&nbsp;Jacob Diamond,&nbsp;Delphine Rioux,&nbsp;Christian Miquel,&nbsp;Stephen Mulero,&nbsp;Clément Lionnet,&nbsp;Francisco J. Peñas,&nbsp;Amaia A. Rodeles,&nbsp;Thibault Datry","doi":"10.1029/2024JG008369","DOIUrl":"https://doi.org/10.1029/2024JG008369","url":null,"abstract":"<p>Stream metabolism is a key biogeochemical process in river networks, synthesizing the balance between gross primary production (GPP) and ecosystem respiration (ER). Globally, more rivers and streams are drying due to climate change and water abstraction for human uses and this can alter the organic carbon residence time leading to decoupled ER and terrestrial organic matter supply. Although the consequences of drying on CO₂ emissions have been recently quantified, its effects on stream metabolism are still poorly studied. We addressed the long-term effects of drying and rewetting events on stream metabolism by monitoring oxygen dynamics at 20 reaches across a drying river network, including perennial (PR) and nonperennial reaches (NPR) for one year. We also calculated several climatic and land use variables and characterized local abiotic conditions and biofilm and sediment communities at five sampling dates. ER was significantly higher in NPR than in PR reaches demonstrating in situ the effects of drying on stream metabolism. When analyzing the long-term drivers of ER and GPP, we found a direct positive effect of drying on ER and a negative effect on GPP. Drying also altered microbial community composition with algal communities from NPRs being different from those in PRs. In the short-term, the total oxygen consumption (respiration) during rewetting events was positively related to the duration of precedent nonflow period. Our results show that drying had an important effect on stream metabolism both in the short- and long term, supporting the need for including NPRs in global estimates of stream metabolism.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008369","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143564843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Suppression of Methanogenesis by Microbial Reduction of Iron-Organic Carbon Associations in Fully Thawed Permafrost Soil","authors":"E. Voggenreiter,&nbsp;L. ThomasArrigo,&nbsp;M. Bottaro,&nbsp;J. Kilian,&nbsp;D. Straub,&nbsp;F. Ring-Hrubesh,&nbsp;C. Bryce,&nbsp;M. Stahl,&nbsp;A. Kappler,&nbsp;P. Joshi","doi":"10.1029/2024JG008650","DOIUrl":"https://doi.org/10.1029/2024JG008650","url":null,"abstract":"<p>Global methane (CH₄) emissions from thawing permafrost peatlands are expected to increase substantially in the future. Net emission of CH₄ depends on the presence of more favorable terminal electron acceptors for microbial respiration, such as ferric iron (Fe(III)). In soils with high OC content, Fe(III) is often coprecipitated with organic carbon (OC). The presence of Fe(III)-OC coprecipitates could either suppress CH₄ emissions due to inhibition of methanogenesis and stimulation of anaerobic methane oxidation coupled to Fe(III) reduction, or enhance emissions by providing additional OC. Here, we investigated the role of Fe(III)-OC coprecipitates in net CH₄ release in a fully thawed, waterlogged permafrost peatland (Stordalen Mire, Abisko, Sweden). We synthesized Fe(III)-OC coprecipitates using natural organic matter from the field site and added them to waterlogged soil in a microcosm experiment and in situ, and followed Fe speciation and changes in greenhouse gas emissions over time. Fe(III)-OC coprecipitates were partially reduced (22%) within 42 days in the microcosm experiment, while almost full reduction (92 ± 4%) occurred in situ within 53 days. This led to a decrease in CH₄ emissions by 94% and 40% in the microcosm and field experiments, respectively, compared to no-coprecipitate controls. A decrease in both RNA-based <i>mcrA</i> copy numbers and relative abundance of detected methanogens indicated that methanogenesis was mainly inhibited by the addition of the coprecipitates due to microbial Fe(III) reduction. In conclusion, Fe(III)-OC coprecipitates temporarily suppress net CH₄ emissions in fully thawed permafrost soils, and might play a similar role in mitigating CH₄ release in other (periodically) flooded soils.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008650","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143565082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnitude Shifts in Aeolian Sediment Transport Associated With Degradation and Restoration Thresholds in Drylands","authors":"Nicholas P. Webb,&nbsp;Brandi Wheeler,&nbsp;Brandon L. Edwards,&nbsp;Jeremy W. Schallner,&nbsp;Neeshia Macanowicz,&nbsp;Justin W. Van Zee,&nbsp;Ericha M. Courtright,&nbsp;Brad Cooper,&nbsp;Sarah E. McCord,&nbsp;Dawn Browning,&nbsp;Saroj Dhital,&nbsp;Kristina E. Young,&nbsp;Brandon T. Bestelmeyer","doi":"10.1029/2024JG008581","DOIUrl":"https://doi.org/10.1029/2024JG008581","url":null,"abstract":"<p>Vegetation change in drylands can influence wind erosion and sand and dust storms (SDS) with far-reaching consequences for Earth systems and society. Although vegetation is recognized as an important control on wind erosion and SDS, the interactions are not well described at the landscape level or in the context of dryland ecosystem change. The transition of sites from one ecological state to another (e.g., grassland to shrubland) is typically associated with changes in the composition, cover, and structure of vegetation, which influence drag partitioning and wind shear velocities that drive aeolian sediment transport. Here, we quantify the magnitude and direction of aeolian sediment transport responses to ecological state change in the northern Chihuahuan Desert and identify thresholds associated with state transitions. Our results show aeolian sediment mass flux (<i>Q</i>) increased from ∼1 to 10 g m⁻¹ d⁻¹ in historical grassland with scattered shrubs to ∼10–100 g m⁻¹ d⁻¹ following shrub invasion and decline in perennial grass cover to ∼100–10,000 g m⁻¹ d⁻¹ in shrubland following complete grass loss. The magnitude shifts were associated with critical perennial grass cover thresholds governing nonlinear increases in <i>Q</i> across ecological state transitions. Grass recovery in shrubland reduced <i>Q</i> to rates similar to those in historical grasslands—a multiple order of magnitude reduction. Our results show that crossing degradation and restoration thresholds between alternative ecological states can have a profound effect on the magnitude and spatiotemporal variability of aeolian sediment transport and primacy in determining patterns of wind erosion and dust emissions in vegetated drylands.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008581","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143564809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Resolution Sensors Reveal Nitrate and Dissolved Silica Dynamics in an Arctic Fjord","authors":"Alexander D. Beaton,&nbsp;Katharine R. Hendry,&nbsp;Jade E. Hatton,&nbsp;Matthew D. Patey,&nbsp;Matthew Mowlem,&nbsp;Geraldine Clinton-Bailey,&nbsp;Patricia Lopez-Garcia,&nbsp;E. Malcolm S. Woodward,&nbsp;Lorenz Meire","doi":"10.1029/2024JG008523","DOIUrl":"https://doi.org/10.1029/2024JG008523","url":null,"abstract":"<p>Subglacial weathering releases biologically important nutrients into meltwaters that have the potential to influence downstream ecosystems. There is a need to understand how accelerated glacial retreat could impact biogeochemical cycling in coastal regions in the near future. However, fjords—important gateways connecting the Greenland ice sheet and coastal oceans—are highly heterogeneous environments both in space and time. Here, we investigate temporal variability of nutrient dynamics in a glacier-fed fjord (Nuup Kangerlua, Greenland) using a high resolution record of nitrate + nitrite (∑NO_x) and dissolved silica (DSi), coupled with temperature and salinity, using submersible in situ sensors. During a 3-month monitoring period (14th June to 13 September 2019), ∑NO_x varied between 0.05 and 10.07 μM (±0.2 μM), whereas DSi varied between 0.35 and 14.98 μM (±0.5 μM). Both nutrients started low (following the spring bloom) and increased throughout the monitoring period. Several large peaks in both nutrients were observed, and these can largely be associated with meltwater runoff and upwelling events. Peaks in DSi were likely the direct result of glacial meltwater pulses, whereas elevated ∑NO_x concentrations in the fjord system were likely the result of meltwater-induced upwelling of marine sources. However, we did not observe a case of simple conservative mixing, suggesting that other processes in the fjord system (e.g., differential biological uptake and remineralization) may decouple the relationship between the two nutrients. This data set was used to investigate the biogeochemical impact of changes in glacier meltwater input throughout the melt season.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008523","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143533381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preferential Groundwater Discharges Along Stream Corridors Are Disregarded Sources of Greenhouse Gases","authors":"A. M. Bisson,&nbsp;F. Liu,&nbsp;E. M. Moore,&nbsp;M. A. Briggs,&nbsp;A. M. Helton","doi":"10.1029/2024JG008395","DOIUrl":"https://doi.org/10.1029/2024JG008395","url":null,"abstract":"<p>Groundwater delivery of greenhouse gases (GHGs) to stream banks and riparian areas, before mixing with surface waters, has not been well quantified. We measured preferential groundwater delivery of GHGs to stream banks within three stream reaches, and found that stream banks with discharging groundwater emitted more CO₂ and were sources of N₂O compared to stream banks without actively discharging groundwater, which emitted less CO₂ and were N₂O sinks. At one of our stream reaches, groundwater CO₂ and N₂O concentrations were 1.4–19.2 and 1.1–40.6 times higher than those in surface water, respectively, and groundwater delivery rates of CO₂ and N₂O were 1.5 and 1.6 times higher than surface water emissions per unit area. On average, 21% (range 0%–100%) of CO₂ and N₂O were emitted at the stream bank before mixing with surface waters. Preferential groundwater GHG emissions may contribute substantially to stream corridor emissions and may be underestimated when using a channel-centric approach to estimate riverine GHG budgets.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143533380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon Burial (in)Efficiency: Tracking the Molecular Fingerprint of In Situ Organic Matter Burial Using a 30-Year Freeze-Core Series From a Northern Boreal Lake (Nylandssjön, Sweden)","authors":"Richard Bindler,&nbsp;Julie Tolu,&nbsp;Christian Bigler,&nbsp;Johan Rydberg,&nbsp;Antonio Martínez Cortizas","doi":"10.1029/2024JG008397","DOIUrl":"https://doi.org/10.1029/2024JG008397","url":null,"abstract":"<p>Organic carbon (OC) burial rates in northern lakes are estimated to have increased by 2–3 fold over the past 150 years. However, assessing OC burial efficiency is challenging because (a) long-term (decadal) process are difficult to study in situ, and (b) sediment organic matter (OM) consists of thousands of different compounds from both terrestrial and aquatic sources, which are subject to different degrees of degradation, transformation, or preservation. Here, we used pyrolysis–gas chromatography/mass spectrometry to track changes in the organic molecular composition of individual varve years in a series of sediment freeze cores collected during 1979–2010, allowing us to assess diagenetic changes over ≤31 years (or 12.5 cm depth). As predicted from previous work, the greatest losses over time/depth (18–19 years; 8.5 cm) are for compounds indicative of fresh OM, both terrestrial (e.g., levosugars with 58%–77% lost) and particularly aquatic origin (e.g., phytadiene and phytene amongst chlorophylls with 40%–82% lost). This high variability in degradation of specific compounds has implications for interpreting past changes in C and N. Although OM composition changes only slightly beyond 20 years (8.5 cm), the chlorophyll:lignin ratio (fresh vs. degraded compounds) continues to decline to 31 years (12.5 cm) and is predicted to continue up to 100 years (37 cm depth). In most northern lakes, indications of OM degradation to these depths correspond to sediment ages of 50 to &gt;150 years, suggesting that much of the recent increase in OC burial in northern lakes does not represent permanent sequestration of C.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008397","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}